What if you dont even use dd, just `wget. (and when you want to have the world's fastest img downloader, every second counts.)Īdditionally, in my script I go a couple steps further by loading the first 100MB of the img into cache first, and also it uses the buffer package to overcome I/O bottlenecks for maximum efficiency. It usually cut down on download time by around 3 seconds. In my tests, I found it gives a bit of a buffer. The cp command (which is very fast in my tests) uses just 128KB block size (see strace cp.
Just for my interest, why are you using "bs=10M" for the dd command? Now I just use "cp" - its simple to use and fast enough in practice (slightly faster than dd bs=1m) I gave up trying to calculate everything and produce an optimal C program! So, given that the disk read times are near zero for this case only, whats the best read/write block size to give dd for the optimal overlap between reads and writes? įor example, I usually download the image to a memory disk, then uncompress it and copy it to the raw device.
Given all the above variables, any simple benchmark results will be meaningless.
KALI RASPBERRY PI 3 DOWNLOAD .XZ EXTENSION VERIFICATION
Its incredibly complicated given: different read/download speeds, decompression speeds, indeterminate overlap between reads and writes, disk write speeds, variable asynchronous disk block prefetch ranges, "sync" time, verification time, etc etc Believe it or not, with enough optimization, it can be faster to download an img, extract it, and flash it to a SD card, than to flash a local, pre-extracted.
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